TILLAMOOK COUNTY EMERGENCY MANAGEMENT: National Weather Service – Weather Forecast Office Portland Friday, Dec 20, 2024

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National Weather Service
National Oceanic and Atmospheric Administration
Active Weather This Weekend (12/20) through Next Week – A Quick Update
KEY POINTS
• A series of weather systems will bring widespread rain, periods of gusty winds, and high elevation Cascade snow to the region Saturday through next week.
• Rivers could rise slightly due to rainfall amounts Saturday (12/21) – Tuesday (12/24), but the time period of most concern for river flooding is with a potentially stronger storm system late Wednesday (12/25) – Thursday (12/26) and beyond. Uncertainty in river flooding potential next week remains high due to high uncertainties in rain amounts over river basins. Continue to monitor water.noaa.gov/wfo/pqr to view latest river forecasts and flood probabilities.

• Cascade snow will mainly remain above pass level (5,000-6,000+ ft) through Monday (12/23). Snow levels may fall below pass level Tuesday (12/24) and beyond, though mainly during lighter periods of precipitation, resulting in limited snow amounts over passes.
• Gusty winds expected along the coast with each weather system through Tuesday (12/24). Gusts up to 40-50 mph at times could produce downed tree limbs and weak trees. Widespread breezy to gusty winds possible Wednesday night (12/25) into Thursday (12/26) with stronger gusts along the coast which could produce downed trees and powerlines and localized power outages.
• Active weather over the Pacific will bring periods of hazardous seas and gales to the coastal waters Saturday (12/21) through next week. There is a 60-80% probability of significant wave heights exceeding 20 ft on Saturday (12/21) through Wednesday (12/25). Highest seas are currently expected on Monday (12/23)
CHANGES FROM PREVIOUS BRIEFING
-Reduced rain risk level from “minor” to “little to no risk” Saturday (12/21) through Monday (12/23).
-Upgraded Hazardous Seas to Moderate risk Saturday (12/21) through Monday (12/23), and Wednesday (12/25).
-Added rain and wind to Thursday (12/26) portion of the matrix for most areas – Gales and Hazardous seas Coastal Waters.